This invention relates to a method for face-to-face weaving pile fabrics, whereby weft yarns are inserted between binding warp yarns and pile warp yarns so that two backing fabrics are woven one above the other in which groups of three weft yarns are inwoven at different levels in respective openings between binding warp yarns crossing each other, and in which pile warp yarns are alternately interlaced in the top and the bottom backing fabric over a weft yarn in order to form pile according to a two-shot weave.
In order to weave carpets with a high pile density on a weaving machine both the reed pitch (the set-up) of this machine will be set high (e.g. 500 to 512/m) and a high pile row density (e.g. 8 to 10 pile rows per cm) will be implemented. For this purpose the so-called single rapier weaving method will preferably be applied because with this method a pile row can be formed on each weft yarn in the carpet.
When use of the double rapier weaving method is desired then with a two-shot weave twice as many weft yarns as pile rows will have to be inserted and with a three-shot weave three times as many weft yarns as required pile rows. With regard to weft insertion performance it is however desirable to select the double rapier weaving method (whereby in each weft insertion cycle two weft yarns are inserted one above the other), in preference to the single rapier weaving method. Furthermore the pile is held straighter by a two-shot weave because each pile leg is borne by a weft yarn located on the back and is supported on the pile side by an interjacent weft yarn. However when a great number of pile rows per cm is desired this interjacent weft yarn however prevents the pile row density from being increased. Insufficient pick density is obtained in the fabric. Also with the conventional two-shot weave it is determined that at very high densities the inwoven dead pile warp yarns have a tendency to form undesired loops on the back of the fabric. These dead pile warp yarns furthermore also always remain transparent on the back.
In order to solve the above problem with the double rapier weaving method, a method is known from the Belgian patent no. 1 012 005 A3 with the properties that are mentioned in the first paragraph of this specification. According to this method groups of at least three weft yarns are inwoven in the openings between the successive intersections of the binding warp yarns. A pile warp yarn is moreover according to a two-shot weave alternately woven through on a weft yarn that in relation to the tight warp yarns and the inwoven dead pile warp yarns is located along the pile side (hereinafter called xe2x80x9cfirst weft yarnxe2x80x9d), and subsequently not woven through on a weft yarn of the same group that in relation to the tight warp yarns and the inwoven dead pile warp yarns is located on the back (hereinafter called xe2x80x9csecond weft yarnxe2x80x9d). The dead pile warp yarns are divided inwoven in the top and the bottom backing fabric, and extend on the pile side of the tight warp yarns between the first mentioned (first) weft yarn and another weft yarn located on the pile side of the tight warp yarns (hereinafter called xe2x80x9cthird weft yarnxe2x80x9d). In this manner the first, second and third weft yarn of each group come to lie in three different planes (at three different levels), through which they are pressed more or less one above the other and enable a great weft density and consequently also a great pile row density. The pattern of the fabric also remains well visible on the back and the inwoven dead pile warp yarns are no longer transparent on the back of the pile fabric. By alternating a through-woven pile tuft with a non-through-woven one the pile warp yarn consumption is furthermore also reduced.
In this manner weaving carpets mechanically with a greater pile density is achieved, for example with a row adjustment of 512/m and a pile row density of 13.5 or 27 weft yarns per cm in the two-shot weave according to FIG. 1 of the above mentioned Belgian patent.
In this patent it is described how such a pile fabric can be woven with four weft yarns per group according to the so-called double rapier weaving method, whereby in each weft insertion cycle two weft yarns are inserted one above the other.
A purpose of this invention is to find an efficient method according to which such pile fabrics can be woven with three weft yarns per group in a very productive manner.
This purpose is according to this invention achieved by providing a method with the characteristics from the first paragraph of this specification whereby in series of four successive weft insertion cycles in each case three weft yarns are inserted for the top backing fabric and three weft yarns for the bottom backing fabric.
This method makes it possible to implement the face-to-face weaving of a pile fabric whereby the pile is formed very efficiently and with a great productivity according to a two-shot weave. The method is practicable on a weaving machine that is provided for inserting two or more weft yarns per weft insertion cycle, whereby in certain weft insertion cycles less weft yarns are inserted. Moreover weaving can be effected both with and without lancets. Since furthermore only three weft yarns are provided in each opening between binding warp yarns crossing each other pile fabrics with a particularly high pile density can be woven according to this method.
Another object of this invention is a pile fabric manufactured according to this method, in particular a carpet, with a backing fabric in which groups of three weft yarns are inwoven in respective openings between binding warp yarns crossing each other, and in which non-pile-forming pile warp yarns and tight warp yarns are inwoven, and with pile yarns that form pile loops around weft yarns. Through the excellent productivity of the weaving method the production costs of these fabrics can be reduced while very high pile densities are achievable.
This method is preferably so implemented that in each series of four weft insertion cycles there are two cycles in the course of which in each case two weft yarns are inserted, while in the course of the two other cycles in each case only one weft yarn is inserted.
This method has an optimum productivity if it is implemented on a weaving machine that comprises means for inserting at least two weft yarns per weft insertion cycle, while in the course of the cycles in which only one weft yarn is inserted either one weft insertion means is disengaged or no weft yarn is provided to one weft insertion means.
The two weft yarns that are inserted in the course of a same cycle are moreover preferably in each case inwoven respectively in the top and the bottom backing fabric.
In each backing fabric tight warp yarns can be provided and non-pile-forming pile warp yarns are inwoven, and of each group of weft yarns a first and a second weft yarn can be provided respectively along the pile side and along the back of the tight warp yarns and the inwoven pile warp yarns, and a third weft yarn can be provided between on the one hand the tight warp yarns and on the other hand the inwoven pile warp yarns.
Depending on the insertion sequence and inweaving of the weft yarns inserted on their own the method according to this invention can be implemented differently. Thus for example in the course of each series of four successive weft insertion cycles,
either a third weft yarn for the top backing fabric and a third weft yarn for the bottom backing fabric are single inserted in the course of respective weft insertion cycles;
or a third weft yarn for the top backing fabric and a second weft yarn for the bottom backing fabric are single inserted in the course of respective weft insertion cycles;
or a second weft yarn for the top backing fabric and a third weft yarn for the bottom backing fabric are single inserted in the course of respective weft insertion cycles;
or a third weft yarn for the top backing fabric and a first weft yarn for the bottom backing fabric are single inserted in the course of respective weft insertion cycles;
or a second weft yarn for the top backing fabric and a first weft yarn for the bottom backing fabric are single inserted in the course of respective weft insertion cycles.
Because of the fact that the three weft yarns of each group are inwoven in a backing fabric at a mutually different level in an opening between crossing binding warp yarns the pile row density can still further be increased.
If furthermore in each backing fabric, the pile-forming pile warp yarns are alternately interlaced over a second and a third weft yarn, the pile warp yarn consumption is reduced. This has the effect of decreasing the production costs.
In the aforesaid Belgian patent BE-1 012 005 it is illustrated in what manner possibly occurring mixed contours can be prevented according to a known method. Mixed contours occur among others in those locations in the fabric where the pile formation of a first pile warp yarn is stopped and is immediately followed by the pile formation of a second pile warp yarn (e.g. in order to make another color visible in the fabric), while the non-pile-forming parts of the first and the second pile warp yarn, respectively before and after this pile change are inwoven in the same backing fabric. The last pile tuft of the first pile warp yarn in the fabric and the first pile tuft of the second pile warp yarn in the fabric are then inwoven between the same two weft yarns, and cause mixed contours. In order to prevent this with the above described two-shot weave it is known that one or both pile warp yarns have to be interlaced over a weft yarn located along the back before allowing them to form pile, respectively be inwoven as dead pile warp yarns. This has the disadvantage that the pattern of the fabric is marred on the back by so-called double points.
Another purpose of this invention is to provide a method with the above mentioned characteristics, according to which a pile fabric can be woven in which mixed contours are prevented but of which the pattern is also shown perfectly on the back of the fabric.
This purpose if achieved by a method according to which the last interlacing of a first pile warp yarn that stops forming pile and is inwoven in one of the backing fabrics and the first interlacing of a second pile warp yarn that is inwoven in the aforesaid backing fabric and starts forming pile is implemented over the same weft yarn, while this weft yarn extends along the pile side of the fabric in relation to pile warp yarns and/or tight warp yarns inwoven in the backing fabric.
The aforesaid first and second pile warp yarn are interlaced together over a weft yarn that does not extend along the back of the pile fabric, so that these pile warp yarns are not visible on the back and no longer form double points that mar the appearance of this back.
These and other characteristics and distinctive features of this invention are described in the following more detailed specification of a possible method according to this invention and of a carpet woven according to this method. This specification only has the purpose of explaining the invention on the basis of an example and may therefore in no way be considered as a restriction on the scope of this patent application.